This invention relates to a method for making an engine cylinder and more particularly to an improved method for making a composite cylinder having a liner and surrounding material formed from different metals.
As noted in my aforenoted copending application, it has been the practice to form cylinders from liners made from cast iron or the like with a surrounding cylinder block formed from a light weight metal such as aluminum or an aluminum alloy. Although this construction is highly satisfactory, there are certain difficulties in forming the cast iron liner, particularly where the device is used as a two cycle engine and ports must extend through the liner. It has previously been the practice to form the liner from a flat sheet and the ports are stamped into this flat sheet. The sheet is then rolled into a cylindrical shape and is joined, as by welding, so as to form the completed liner. Such a method has a number of disadvantages, as is noted in my aforenoted copending application.
In my aforenoted application, the liner is made from a cylindrical pipe section and the port openings are formed by punching openings in the liner. Although this has many advantages and overcomes the disadvantages of the prior art constructions, there still can be improvements made in the manner in which the port openings are punched. It is, therefore, a primary object of this invention to provide an improved method for forming the port openings in a cylindrical liner section.
It is yet a further object of this invention to provide an improved punching process for forming openings in a cylindrical liner that can be utilized as the cylinder liner for an internal combustion engine of the two-cycle type.
It is also another object of the invention to provide an improved composite cylinder construction.